The hex carrier trimmed outer ASCII whitespace with a global
start|end-anchored regex. For an invalid carrier with a long interior
whitespace run, the end branch was retried at every position of the run,
so rejection took quadratic time (about 18 s for a 200 KB run) and a few
hundred KB could exhaust the worker deadline instead of returning the
documented invalid-format error. Trim with index scans over the same
ASCII whitespace set.
Co-authored-by: gensokyo-dev <342580529+gensokyo-dev@users.noreply.github.com>